Unfortunately, most of the more than 750 million alkaline batteries sold each year to power our cameras, flashlights and Discmans are landfilled and incinerated, not recycled.

The chemicals in these batteries — particularly cadmium — present a major health hazard if they leak from their corroded metal jackets. Cadmium is a probable human carcinogen, and it can also affect kidney and lung function.

Several states, including Maine, Vermont and Florida, have passed legislation prohibiting incineration and landfilling of mercury-containing and lead-acid batteries, according to the U.S. Environmental Protection Agency's Office of Product Stewardship.

Regardless of your home state's attitude on batteries, you should contact your town's solid waste office to see if there are any planned Hazardous Waste Collection Days. Batteries awaiting recycling should be stored separately from other hazardous materials in a cool and dry area.

Or take advantage of some of the increasingly popular national battery recycling programs. Since 1989, 13 states have adopted laws (including battery labeling requirements) to encourage the collection and recycling of used rechargeable batteries. In 1996, Congress passed the Mercury-Containing and Rechargeable Battery Management Act, which helps facilitate the Rechargeable Battery Recycling Corporation's (RBRC) nationwide take back program.

According to RBRC, some rechargeable batteries can go through 1,000 cycles. RBRC recycles million of batteries each year, collecting used batteries from more than 30,000 depositories in the U.S. and Canada, many at large retailers such as Home Depot, Best Buy and Target. The RBRC collects only nickel-cadmium, nickel-metal hydride, lithium ion and small sealed-lead batteries.

The Big Green Box battery-recycling program provides consumers, companies and government agencies with a simple method for recycling both batteries and portable electronic devices (cellphones, cameras, calculators and laptops) without having to drive to a recycling center. You prepay for a sturdy cardboard box (the consumer version is $58) that will hold up to 40 pounds of recyclables. The cost of the box includes all shipping, handling and recycling fees. You keep the box handy, filling it with old batteries and equipment as you go  and simply ship it to The Big Green Box address when it's full.

Dear EarthTalk: How do sewer treatment plants threaten estuaries?

— Jean T. Castagno, Old Saybrook, Connecticut

Estuaries are partially enclosed bodies of water where freshwater and saltwater mix. They are key coastal habitats for many a species of mammal, fish and bird  and are used as spawning grounds for much of our nation's commercial fish and shellfish. The wetlands associated with estuaries buffer uplands from flooding.

Estuaries also provide many recreational opportunities, such as swimming, boating and bird watching. Chesapeake Bay, San Francisco Bay, Boston Harbor, Tampa Bay and Puget Sound are all examples of U.S. estuaries, but one that is particularly plagued by sewer plant drainage is the Northeast's Long Island Sound.

Norwalk, Connecticutbased Save the Sound reports that 10 percent of the U.S. population lives within 50 miles of Long Island Sound. That's a lot of people and a lot of sewage. According to the Natural Resources Defense Council (NRDC), "Sewage treatment plants discharge more than one billion gallons of treated effluent into the Sound each day."

Sewage plants wreak havoc because their daily deposits contain nitrogen, which over-fertilizes the water and causes explosive growth in marine plants. These plants eventually die, sink and decompose. The unnatural amount of decaying material depletes dissolved oxygen levels, creating a condition called "hypoxia," which Save the Sound says has diminished fish populations, reduced lobster growth rates, and negatively affected slow-moving species such as starfish and bay anchovy in Long Island Sound.

Connecticut and New York have both committed millions to improve the health of the Sound with habitat restoration and upgraded sewage plants. There has already been a 19 percent reduction in nitrogen discharges since 1990. A number of state and federal organizations have also banded together to host National Estuaries Day, meant to promote the importance of estuaries and the need to protect them.